Method of and apparatus for producing uninterruptible power

ABSTRACT

Uninterruptible power is supplied to a load connected to a power line by connecting the power line to a rotatable member that includes a Rankine cycle turbine coupled to a device that operates as a motor when line power is operative thereby rotating the member at a standby rotational speed so that a predetermined amount of kinetic energy is stored in the rotating member, and that operates as a generator when the line power is inoperative and the member is rotated by the application of vaporized working fluid to the turbine. Working fluid is vaporized and maintained at an operational temperature level only when the line power is inoperative. The working fluid is held at a standby temperature level, preferably greater than the operational temperature level, while the power line is operative whereby the working fluid contains a predetermined amount of stored thermal energy while the power line is operative. In response to loss of line power, vaporized working fluid is applied to the turbine thereby rotating the rotatable member whereby the turbine rotates the member at a nominal operational speed that preferably is less than the standby rotational speed. Finally, in response to the loss of line power the device is connected to the load whereby the stored thermal energy in the working fluid and the stored kinetic energy in the rotating member are converted by the device to power for the load.

TECHNICAL FIELD

[0001] This invention relates to a method of and apparatus for producingpower, and more particularly, to a method of and apparatus for producinguninterruptible power for communication systems that are located inurban areas or in the vicinity of towns and also stand alone powersystems for communication installations in remote areas.

BACKGROUND OF THE INVENTION

[0002] Uninterruptible power systems particularly in communicationsystems often utilize photovoltaic systems, thermoelectric generators(TEG) or organic Rankine cycle energy converters. A diesel engine baseduninterruptible power sources (UPS) utilizes batteries or a flywheel tosupply an electrical load when line power drops out and until the dieselcan start and bring the generator on line.

[0003] In telecommunications systems, redundant organic Rankine cycleenergy converters each operating at partial load have been used so that,failure of one converter causes the other converter to supply the fullload. A transient period, until which the second energy converterdelivers the full load, which can last from a few minutes up to about20-50 minutes can be reduced bya standard battery that delivers a fewampere-hours.

[0004] Since 1976, as part of the Trans-Alaska Pipeline Project, a largenumber of stations have been operating each using a single OrganicRankine cycle turbine unit as a warm standby unit to ensure the requiredreliability. In such a standby unit, a line-operated electric heaterunder themostatic control provides external heat to a vapor generator ofthe unit to maintain the working fluid at about 120° F. When powerfails, the main burner is activated quickly bringing the organic vaporRankine cycle turbine unit on line delivering full power to the stationas described in Trans-Alaska Pipeline, Remote Gate Valve EquipmentBuildings, Operation and Maintenance Manual, Volume II, Ormat EnergyConverter Model 155, April 1976).

[0005] In a related system disclosed in U.S. Pat. No. 4,982,569, thedisclosure of which is hereby incorporated by reference, a hybrid powersystem is disclosed that includes an intermittently operable non-fuelconsuming power generator, such as a photovoltaic cell array, or a windgenerator, connected through a control-circuit to a battery for changingthe same and for supplying current to a time-wise, substantiallyconstant, electrical load. In addition, this hybrid power plant includesan electric generator connected to an intermittently operable primemover, such as a Rankine cycle organic vapor turbogenerator for chargingthe battery and supplying current to the electrical load when the primemover is operated, and a sensor for sensing at least one electricalparameter of the power plant. With such an arrangement, the prime moveris operable only when the power generator is not operating.

[0006] In another related system disclosed in U.S. Pat. No. 4,760,705,the disclosure of which is hereby incorporated by reference, theinvention disclosed therein relates to a Rankine cycle power plantoperating with an improved working fluid, the working fluid being acompound selected from the group consisting of bicyclic aromatichydrocarbons, substituted bicyclic aromatic hydrocarbons, heterocyclicaromatic hydrocarbons, substituted heterocyclic aromatic hydrocarbons,bicyclic or heterobicyclic compounds where one ring is aromatic and theother condensed ring in a non-aromatic, and their mixtures. In a furtheraspect of the invention disclosed in this U.S. patent, a binary Rankinecycle power plant is provided in which the condenser of the hightemperature and pressure turbine is cooled by a different working fluidwhich is vaporized thereby and supplied to a low temperature andpressure turbine.

[0007] Israel Patent 43547 discloses a further related system anddiscloses a rotor for a homopolar electrical machine.

[0008] Batteries are used in all the telecommunication projects toprovide DC power to the telecom equipment and the reliability andavailability of the system depends strongly on the batterycharacteristics.

[0009] The batteries have a limited lifetime and if not properly chargedand maintained they have to be replaced a few times during the life of aproject estimated as 20-25 years.

[0010] In addition, because the battery condition cannot be correctlyassessed, battery failure occurs without any kind of advance notice,station shut-down often occurs unexpectedly. Moreover, the battery failswhen they are actually needed so that, when there is an electrical gr idpower outage, the diesel generator fails when it is attempted to startit consequently causes the battery, UPS and diesel generator not toprovide power.

[0011] It is therefore an object of the present invention to provide anew and improved method of and apparatus for providing uninterruptiblepower wherein the disadvantages as outlined are reduced or substantiallyovercome.

SUMMARY OF THE INVENTION

[0012] According to the present invention, an uninterruptible powersupply associated with a power line for supplying a load includes a loadcircuit connected said power line to said load for powering the samewhile said power line is operative, and a rotatable member including aRankine cycle turbine coupled to a device that operates as a motor whenline power is inoperative and this member is rotated by the applicationof vaporized working fluid to the turbine. A driver circuit connects thepower line to the device thereby rotating the rotatable member at astandby rotational speed while the power line is operative for storing apredetermined amount of kinetic energy in the rotating member. The powersupply also includes a boiler containing working fluid, a burnerassociated with said boiler operable to produce vaporized working fluidand to maintain the same at an operational temperature level when theline power is inoperative, and resistance heater associated with theboiler and connected to the power line for holding the working fluid ata standby temperature level while the power lind is operative, thestandby level of the boiler being preferably greater than theoperational level of the boiler whereby the working fluid contains apredetermined amount of thermal energy while the power line isoperative. A valve is operable to connect the boiler to the turbine forapplying vaporized working fluid to the turbine thereby rotating therotatable member, and a control is responsive to loss of line power (1)for operating the burner, which causes the boiler to produce vaporizedworking fluid, and for operating the valve, which supplies vaporizedworking fluid to the Rankine cycle turbine which thereby rotates themember at a nominal operational speed preferably that is less than thestandby rotational speed, and (2) for connecting the device to the loadwhereby power is supplied to the load while the power line isinoperative, the thermal energy in the working fluid in the boiler andthe predetermined amount of kinetic energy being converted by the deviceto power for the load upon loss of line power.

[0013] In addition, the present invention includes a method forsupplying uninterruptible power to a load connected to a power linecomprising connecting the power line to a rotatable member comprising aRankine cycle turbine coupled to a device that preferably operates as amotor when line power is applied to the device thereby rotating themember at a standby rotational speed for storing a predetermined amountof kinetic energy in the rotating member, and that operates as agenerator when the line power is inoperative, the member being rotatedby the application of vaporized working fluid to the turbine.Additionally, the method includes vaporizing working fluid andmaintaining the same at an operational temperature level only when theline power is inoperable. Furthermore, the method includes holdingworking fluid at a standby temperature level while the power line isoperative, the standby temperature level preferably being greater thanthe operational temperature level whereby the working fluid contains apredetermined amount of stored thermal energy while power line isoperative. In addition, the method includes applying the vaporizedworking fluid to the turbine thereby rotating the rotatable member inresponse to loss of line power whereby the turbine rotates the member ata nominal operational speed that is preferably less than the standbyrotational speed. Moreover, the method includes connecting the device tothe load whereby power is supplied to the load while the power line isinoperative so that the stored thermal energy in the working fluid andthe predetermined amount of kinetic energy are converted to power forthe load upon loss of line power.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments of the present invention are described by way ofexample, and with reference to the accompanying drawings wherein:

[0015] FIGS. 1A-1B are schematic diagrams of an embodiment of thepresent invention showing different modes or phases of operation;

[0016]FIG. 2 is a schematic diagram of an embodiment of the presentinvention;

[0017]FIG. 3 is a schematic diagram of a modification of the embodimentof the present invention shown in FIG. 2;

[0018]FIG. 4 is a schematic diagram of a further modification of theembodiment of the present invention shown in FIG. 2;

[0019]FIG. 5 is a schematic diagram of an additional embodiment of thepresent invention;

[0020]FIG. 6 is a schematic diagram of still another embodiment of thepresent invention; and

[0021]FIG. 7 is a schematic diagram of further embodiment of the presentinvention.

[0022] Like reference numerals and designations in the various drawingsrefer to like elements.

DETAILED DESCRIPTION

[0023] Turning to the Figures, FIGS. 1A and 1B show shematically themain phases of operation of the preferred embodiment of the presentinvention, the phases being designated as Phases 0, 1 a, 1 b and 1 c andrepresenting the configuration of the apparatus as a function of eventsthat occur in the operation of the apparatus. Phase 0 occurs when anelectric utility supplies line power to a load, this phase lasting aslong as line power is operative. In Phase 0, the apparatus is in a hotstandby rotational speed, and working fluid in boiler 53 is maintainedat an operational temperature level by a resistance heater connected tothe line.

[0024] Phase 1 a occurs in response to the loss of line power, andtypically last for a few seconds as spin-down of turbine 0.57 causesgenerator 73 to deliver energy to the load. Upon loss of power, workingfluid is applied to turbine 57 and fuel is delivered to burner 51.

[0025] Phase 1 b typically last for a few minutes after loss of linepower occurs as stored thermal energy in boiler 53 is converted toelectricity and delivered to the load. At the end of phase 1 b, theburner is delivering sufficient heat to the boiler to maintain the sameat an operational temperature level at which the turbine operationsustains the load. At this time, Phase 1 c occurs as long as the lineremains inoperative and the fuel is not exhausted.

[0026] In phase 0 (see FIG. 1A) power is supplied by the electricutility to the load by rectifier 76 as well as the AC input beingsupplied to motor 52 that maintains or drives turbine 57 so that it isrotated. In this phase, electric heater 54, supplied by AC line powersupplied by the utility, preferably maintains the temperature of vaporgenerator or boiler 53 at a temperature above its normal operatingtemperature (normal operation or normal operating conditions beingconditions during phase 1 c described below). However, on the otherhand, the temperature of boiler or vapor generator 53 can be maintainedat the same temperature as that when normal operation takes place (seephase 3 described below). In addition, in phase 0, if preferred, motor52 maintains the speed of turbine 57 above its normal operating speed(normal operation or normal operating conditions being conditions duringphase 1 c described below). However, on the other hand, the speed ofturbine 57 can be maintained at its normal operating speed i.e. duringnormal operation (see phase 1 c described below). In phase 1 a (see FIG.1B), a utility failure occurs so that no line power is available and thepower is supplied to the load for a short period of time (e.g. someseconds) by Rankine cycle turbine 57 utlitizing its inertia or kineticenergy via generator 73 and rectifier 76. Thereafter, in phase 1 b (seealso FIG. 1B), power is supplied to the load by Rankine cycle turbine57via generator 73 and rectifier 76 utlizing the thermal energy presentin boiler or vapor generator 53. In phase 1 c (see FIG. 1B as well),power is supplied by Rankine cycle turbine 57, under its normaloperating conditions, to the load via generator 73 and rectifier 76wherein boiler or vapor generator 53 now supplies the vapors to Rankinecycle turbine 57 from heat supplied from the combustion gases producedby burner 51.

[0027] Thus, the Rankine cycle turbine is maintained at hot standbyconditions wherein the hot standby Rankine cycle turbine is the rotatingRankine cycle turbine 57 and boiler or vapor generator 53 in a state ofincipient rate flow of vaporized working fluid. In such a manner, theRankine cycle turbine system, having the rotating Rankine cycle turbine57 and hot boiler or vapor generator 53, in phase 0, is at hot standbyready to provide the required continuous operation to ensure that theload is continuously supplied with the required power.

[0028] As far as FIG. 2 is concerned, power unit system 10A is providedaccording to an embodiment of the present invention for providinguninterruptible power and includes organic Rankine cycle turbine 57Adesigned to operate as a hot standby organic Rankine cycle turbinesystem 50A. In the present embodiment, hot standby organic Rankine cycleturbine system 50A includes electric motor 52A for rotating the turbinewhen electric power is available from the electric grid. The embodimentalso includes boiler 53A and heater 51A comprising e.g. a burner forcombusting fuel. In addition, the present embodiment includes electricheater 54A for heating the liquid organic working fluid in the boilerwhen electric line power is available from the electric grid or utility.Moreover, in the present embodiment, valve 55A is included that enablesthe supply of organic working fluid vapor to turbine 57A for its nominaloperation, when electric power is not available from the electric grid.

[0029] In operation, when the electric grid or utility is supplyingelectric line power, electric motor 52A rotates turbine 57A via driver75A that receives power from the grid. Line 66A receives sufficientorganic working fluid vapor from boiler 53A, heated by electric heater54A, for supplying fluid only to bearings 56A. Heater, i.e. burner, 51Ais not operated and preferably a flap located on the stack of boiler 53Ais maintained in a closed state by an actuator. Thus, liquid suppliedvia line 66A is supplied to reservoir 64A. This condensate is suppliedvia line 65A where it is cooled to bearings 56A. Condensate exiting thebearings is supplied via pump 67A, e.g. a pitot pump, to reservoir 64Afrom where it is returned to bearings 56A. Electric heater 54A continuesto supply heat to organic working fluid in boiler 53A for compensatingfor fluid finding its way back via line 68A to vessel 69A in heatrelationship with boiler 53A. Thus, under such conditions, the electricgrid supplies power to the load and the organic Rankine cycle turbinesystem is maintained at hot standby.

[0030] When the electric grid does not supply electric power, kineticenergy present in turbine 57A permits power unit 10A to continue tosupply electric power even though no electric power is supplied toelectric motor 52A from the electric grid or utility. Valve 55A isopened by control unit 85A, which senses the state of the line power, inorder that organic working fluid vapor is supplied from boiler 53A viaconduit 71A to turbine nozzle block 70A. Consequently, power is nowproduced by the rotation of organic Rankine cycle turbine 57A rotated byorganic working fluid vapor produced by heat present in the hot organicworking fluid present in boiler 53A. At the same time, the actuatoropens the flap and heater, i.e. burner, 51A, commences operation withthe receipt of a control signal from control unit 85A that also sends acontrol signal to open fuel valve 72A. In addition, control unit 85Asends a control signal to electric heater 54A to stop operation. Therotation of organic Rankine cycle Turbine 57A results in generator 73Aproducing electric power that can be supplied to the load. Thus, now theheat produced by the combustion gasses from burner 51A heats the workingfluid in boiler 53A that produces vapors for supply to turbine 57A.

[0031] When electric power becomes available from the electric grid onceagain, control 85A senses the electric power and sends control signalsto heater, i.e. burner, 51A, to switch off, to the flap to open, toelectric heater 54A to switch on and to close valve 55A so that noorganic working fluid vapor is supplied via this valve to organicRankine cycle turbine 57A. Organic working fluid liquid continues to besuppied to 56A of turbine 57A as previously described via line 66A,reservoir 64A and line 65A.

[0032] Thus, in accordance with the present invention and with referenceto FIG. 2, in standby mode or Phase 0 (see FIG. 1A) when line or utilitypower is available to supply the load, turbine 57A is driven by motor52A. Also in this mode, boiler 53A is heated by resistance or electricheater 54A receiving line power from the utility or electric grid.Working fluid liquid supplied to reservoir 64A is cooled in line 65A andis supplied to bearings 56A for providing lubrication of the bearingsduring rotation of turbine 57A.

[0033] In transient mode, phase 1 a (see FIG. 1B), when utility failureoccurs and line power is interrupted, kinetic energy present in turbine57A permits the turbine to continue rotating so that generator 73Aproduces power that is supplied to the load via rectifier 76A. Also, atthe same time, valve 55A begins to open so that organic working vaporcan be supplied from boiler 53A via conduit 71A to turbine nozzle block70A in order that vapors are supplied to turbine 57A for rotating it. Inaddition, simultaneously, ignition of burner 51A commences whileelectric heater 54A is switched off. Thereafter, in phase. 1 b (see FIG.1B), valve 55A having completed opening and continues to supplie vaporsto turbine 57A using heat present in boiler or vapor generator 53A,generator 73A produces power that is supplied to the load, fuel valve72A opens and burner 51A. Consequently, boiler 53A quickly producesrated flow of vaporized working fluid.

[0034] Subsequently, when line power is unavailable, phase 1 c (see FIG.1B), in an active mode, boiler 53A, heated by the continuous operationof burner 51A, supplies rated flow of vaporized working fluid to turbine57A that drives generator 73A for supplying power to the load.

[0035] Turning to FIG. 3, numeral 10B designates a further embodiment ofa power unit system provided for supplying uninterruptible power inaccordance to the present invention. It comprises a power unit systemvery similar to the embodiment described with reference to FIG. 2 andoperates on an organic working fluid. However, in the embodimentdescribed with reference to FIG. 3, motor/generator 52B is included suchthat when electric power is available at the electric gridmotor/generator 52B operates as a motor for rotating turbine 57B. On theother hand, when no electric power is available on the electric grid,motor/generator 52B operates as an electric generator in order that therotation of turbine 57B results in motor/generator 52B producingelectric power that can be supplied to the load.

[0036] As far as FIG. 4 is concerned, numeral 10C designates anadditional embodiment of the present invention wherein a power unitsystem is provided for supplying uninterruptible power in accordance tothe present invention. Also here, this embodiment is similar to theembodiment described with reference to FIG. 1 and in particular to theembodiment described with reference to FIG. 2 and operates on an organicworking fluid. In the present embodiment rather than using on-off valve55A or 55B as shown in FIGS. 1 and 2 respectively, conduit 59C feeds oneturbine nozzle out several or tens present in nozzle block 70C so that afew percent of the organic working fluid vapors are fed to turbine 57Cvia conduit 59C for rotating it.

[0037] Consequently, when electric power is available at the electricgrid, a small amount of organic working fluid vapor is supplied viaconduit 59C and one nozzle of nozzle block 70C to turbine 57C forrotating the turbine. As a result, there is no need in this embodimentfor an electric motor for rotating turbine 57C when electric power isavailable from the electric grid. In addition, when no electric power isavailable on the electric grid, control valve 86C that receives controlsignals from control unit 85C supplies organic working fluid vapor tothe rest of the nozzles in nozzle block 70C for rotating turbine 57C atfull power.

[0038] In these embodiments, if preferred, electric generator 73A inFIG. 2 can be a synchronous, homopolar, induction or permanent magnetgenerator, while motor 52A can be an induction, synchronous or permanentmagnet motor.

[0039] Thus, in these embodiments, the use of organic Rankine cycleturbine 57, 57A, 57B and 57C rotating when the line power is available,eliminates the need for using a battery or batteries.

[0040] In addition, while the above description refers to the workingfluid as an organic working fluid, the present includes water and itsuse in the Rankine cycle turbine system. In addition, of course, thewater can be used as the working fluid in the Rankine cycle power plantsystems that form part of the previously described embodiments.

[0041] As far as FIG. 5 is concerned, numeral 10D designates anadditional embodiment of the present invention for supplyinguninterruptible power in accordance to the present invention. Basically,this embodiment is similar to previous described embodiments of thepresent invention, except that, in the present embodiment, the waterworking fluid is supplied from water storage tank 90D via pump 56D toboiler 53D. Water storage tank 90D itself is preferably supplied withtreated water from water treatment system 91D furnished with make-upwater. In addition, in this embodiment the low-pressure steam exitingturbine 57D, connected to high frequency asynchronous generator/motor73D, is supplied from turbine exhaust manifold 60D via conduit 92D tostack or chimney 94D for exit to the atmosphere. Thus, turbine 57D hasan atmospheric exhaust, and comprises consequently a back-pressure steamturbine. Furthermore, in an alternative according to the presentinvention, conduit or line 92D is preferably tapered at its outlet tostack 94D in order to assist the draft produced in the stack or chimney.In such a case, flap F3 can be connected externally to conduit or line92D at its outlet 93D. In a further alternative, according to thepresent invention, portion of the exhaust steam exhausting turbine 57Dpresent in conduit or line 92D can be mixed with treated water suppliedto boiler 53D in order to directly preheat the water supplied to theboiler. In a still further alternative, according to the presentinvention, exhaust steam exhausting turbine 57D present in conduit orline 92D can be used to indirectly preheat the treated water supplied toboiler 53D. Condensate produced during such preheating can be suppliedto water storage tank 90D.

[0042] Numeral 10E in FIG. 6 designates a still further embodiment ofthe present invention for supplying uninterruptible power in accordanceto the present invention. Basically, this embodiment is also similar tothe previous described embodiments of the present invention, and inparticular to the embodiment, generator/motor 73E is a synchronous or ahomopolar generator/motor.

[0043] Turning now to FIG. 7, numeral 10F a still further embodiment ofthe present invention for supplying uninterruptible power in accordanceto the present invention. Basically, this embodiment is similar toprevious described embodiments of the present invention, except that, inthe present embodiment, the working fluid, specifically water, iscirculated in power unit SOF with the, aid of pump 56F. In thisembodiment, the low-pressure steam exiting turbine 57F is supplied toturbine exhaust manifold 60F and then to condenser 62F, preferably anair-cooled condenser having a fan for supplying air to the condensertubes, for producing steam condensate that is supplied using pump 56F toboiler 53F. In this embodiment, generator/motor 52F connected to turbine57F can be a high frequency asynchronous generator/motor oralternatively a synchronous or a homopolar generator/motor.

[0044] In operation, when the electric grid or utility is supplyingelectric line power, electric motor/generator 52F operating as a motorrotates turbines 57F via driver 75F that receives power from the grid.Line 66F receives sufficient organic working fluid vapor from boiler53F, heated by electric heater 54F, for supplying fluid only to bearings56F. Heater, i.e. burner, 51F is not operated and preferably a flaplocated on the stack of boiler 53F is maintained in a closed state by anactuator. Thus, liquid supplied via line 66A is supplied to reservoir64F. This condensate is supplied via line 65A where it is cooled tobearings 56F. Condensate exiting the bearings is supplied via pump 67F,e.g. a pitot pump, to reservoir 64F from where it is returned tobearings 56F. Electric heater 54F continues to supply heat to organicworking fluid in boiler 53AF for compensating for fluid finding its wayback via line 68F to vessel 69F in heat relationship with boiler 53F.Thus, under such conditions, the electric grid supplies power to theload and the organic Rankine cycle turbine system is maintained at hotstandby.

[0045] When the electric grid does not supply electric power, kineticenergy present in turbine 57F permits power unit 10F to continue tosupply electric power even though no electric power is supplied toelectric motor 52F from the electric grid or utility. Valve 55F isopened by control unit 85F, which senses the state of the line power, inorder that organic working fluid vapor is supplied from boiler 53F viaconduit 71F to turbine nozzle block 70F. Consequently, power is nowproduced by the rotation of organic Rankine cycle turbine 57F rotated byorganic working fluid vapor produced by heat present in the hot organicworking fluid present in boiler 53F. At the same time, the actuatoropens the flap and heater, i.e. burner, 51F, commences operation withthe receipt of a control signal from control unit 85F that also sends acontrol signal to open fuel valve 72F. In addition, control unit 85Asends a control signal to electric heater 54F to stop operation. Therotation of organic Rankine cycle turbine 57F results in motor/generator52F, now operating as a generator, producing electric power that can besupplied to the load. Thus, now the heat produced by the combustiongases from the burner 51F heats the working fluid in boiler 53F thatproduces vapors for supply to turbine 57F.

[0046] When electric power becomes available from the electric grid onceagain, control 85F senses the electric power and sends control signalsto heater, i.e. burner, SF, to switch off, to the flap to open, toelectric heater 54F to switch on and to close valve 55F so that no steamis supplied via this valve to organic Rankine cycle turbine 57F. Liquidwater continues to be supplied to bearings 56F of turbine 57F aspreviously described via line 66F, reservoir 64F and line 65F.

[0047] While the embodiment described with reference to FIGS. 5, 6 and 7describe a generator/motor driven by turbine 57D, 57E and 57F, ifpreferred, a separate generator and motor, e.g. like motor 52A andgenerator 73A described with reference to FIG. 1, can be used instead ofthe generator/motor.

[0048] In addition, it should be pointed out that the present inventionincludes as well the method for operating the apparatus disclosed withreference to above-described figures.

[0049] Moreover, it should be pointed out that, at present, theembodiment of the present invention described with reference to FIG. 3is considered the best mode for carrying out the present invention.

[0050] Furthermore, when an organic working fluid is used as the workingfluid in the Rankine cycle turbine system or systems, the working fluidis preferably chosen from the group chlorobenzene—dichlorobenzene,trichlorobenzene; bicyclic aromatic hydrocarbons; substituted bicyclicaromatic hydrocarbons, heterocyclic aromatic hydrocarbons, substitutedheterocyclic aromatic hydrocarbons, bicyclic or heterobicyclic compoundswhere one ring is aromatic and the other condensed ring is non-aromatic,and their mixtures such as naphthalene, 1-methyl-napthalene,1-methyl-napthalene, tetralin, quinolene, benzothiophene; an organic,alkylated heat transfer liquid fluid or a synthetic alkylated aromaticheat transfer fluid, e.g. thermal oils such as Therminol LT fluid (analkyl substituted aromatic fluid), Dowtherm J (a mixture of isomers ofan alkylated aromatic fluid), isomers of diethyl benzene and mixtures ofthe isomers and butyl benzene.

[0051] Furthermore, while the above description refers to a hot standbymode of operation, the present invention is also operational in a warmstandby mode wherein a battery is provided in addition to the Rankinecycle turbine system described above and detailed in the above-mentionedembodiments. In the warm standby mode, the battery provides power to theload after the line power has stopped supplying power to the load or theelectric utility had failed and until the Rankine cycle turbine suppliesthe required power to the load. In this embodiment, the boiler ismaintained warm (e.g. at about 60° C.) by e.g. an electric heater, like54A shown in FIG. 2, described above so that the period of time neededfor the Rankine cycle turbine to start supplying the required powerlevel to the load is relatively short (e.g. up to a half hour). Thus,the battery used in this configuration is relatively small.

[0052] In addition, the units described in accordance with the presentinvention, can be used in a cold standby configuration, wherein a largebattery is provided for supply power to the load when line power failsuntil nominal power is produced by the power unit. In such a system, thepower until will commence operation when line power drops out.

[0053] Furthermore, in accordance with the present invention, the powerproduced by the generator of the Rankine cycle turbine unit, e.g. 73A ofFIG. 2, etc., is preferably supplied to the load so that it thresholdvoltage is lower than that supplied to the load when line power isavailable. This permits the power produced by the Rankine cycle turbineunit to be supplied automatically to the load once the power from thegrid or power utility had dropped below a certain predeterminedthreshold value. In the arrangement provided in accordance with thepresent invention, the need for using an additional or externalrectifier can be saved. However, on the other hand, the line power canbe supplied to the load via an additional or external rectifier.

[0054] In addition, in accordance with the present invention, it shouldbe pointed out that operation of Rankine cycle turbine unit usingTherminol or Dowtherm J permits the unit to operate at a relatively hightemperature. When operating with these working fluids, low losses inparticular during standby operation when grid or utility power isrotating the turbine are achieved. In addition, such high temperatureoperation can reduce the size of the condenser.

[0055] It is believed that the advantages and improved results furnishedby the method and apparatus of the present invention are apparent fromthe foregoing description of the invention. Various changes andmodifications may be made without departing from the spirit and scope ofthe invention as described in the claims that follow.

What is claimed is:
 1. An uninterruptible power supply associated with apower line supplying a load comprising: a) a load circuit connectingsaid power line to said load for power the same while said power line isoperative; b) a rotatable member including in a Rankine cycle turbinecoupled to a device that operates as a motor when line power is appliedto said device thereby rotating said member, and as a generator whenline power is inoperative and said member is rotated by the applicationof vaporized working fluid to said turbine; c) a driver circuitconnecting said power line to said device thereby rotating saidrotatable member at a standby rotational speed while said power line isoperative for storing a predetermined amount of kinetic energy in therotating member; d) a boiler containing working fluid; e) a burnerassociated with said boiler operable to produce vaporized working fluidand to maintain the same at an operational temperature level when saidline power is inoperative; f) a resistance heater associated with saidboiler and connected to said power for holding said working fluid at astandby temperature level while said power line is operative, saidstandby level of said boiler being greater than said operational levelof said boiler whereby said working fluid contains a predeterminedamount of thermal energy while said power line is operative; g) a valveoperable to connect said boiler to said turbine for applying vaporizedworking fluid to said turbine thereby rotating said rotatable member; h)a control responsive to loss of line power (1) for operating said burnerthat causes said boiler to produce vaporized working fluid and foroperating said valve that supplies vaporized working fluid to saidRankine cycle turbine which thereby rotates said member at a nominaloperational speed that is less than said standby rotational speed, and(2) for connecting said load whereby power is supplied to said loadwhile said power line is inoperative, said thermal energy in saidworking fluid in said boiler and said predetermined amount of kineticenergy being converted by said device to power for said load upon lossof line power.
 2. A power supply according to claim 1 in which saidworking fluid is an organic working fluid.
 3. A power supply accordingto claim 2 in which said working fluid is Dowtherm J.
 4. A power supplyaccording to Claim 1 wherein said member is mounted on bearings and saidturbine exhausts heat-depleted working fluid while said valve isoperated, and said power supply includes a condenser for condensingheat-depleted working fluid exhausted by said turbine and producingcondensate, and conduits for returning said condensate to said boiler aportion of which is used to lubricate said bearings.
 5. A power supplyaccording to claim 4 wherein said boiler is constructed and arranged toproduce a relatively small quantity of vaporized of vaporized workingfluid while said power line is operative, said power supply including anexhaust manifold interposed between said turbine and said condenser forpassing heat-depleted working fluid to said condenser, and said powersupply includes a conduit for supplying a relatively small quantity ofvaporized working fluid to said exhaust manifold whereby condensatelubricants said bearings while said power line is operative.
 6. A methodfor supplying uninterruptible power to a load connected to a power line,said method comprising: a) connecting said power line to a rotatablemember comprising a Rankine cycle turbine coupled to a device thatoperates as a motor when line power is applied to said device therebyrotating said member at a standby rotational speed for storing apredetermined amount of kinetic energy in said rotating member, and thatoperates as a generator when said line power is inoperative and saidmember is rotated by the application of vaporized working fluid to saidturbine; b) vaporizing working fluid and maintaining the same at anoperational temperature level only when said line power is inoperable;c) holding working fluid at a standby temperature level while said powerline is operative, said standby temperature level being greater thansaid operational temperature level whereby said working fluid contains apredetermined amount of stored thermal energy while power line isoperative; d) applying said vaporized working fluid to said turbinethereby rotating said rotatable member in response to loss of line powerwhereby said turbine rotates said member at a nominal operational speedthat is less than said standby rotational speed; and e) connecting saiddevice to said load whereby power is supplied to said load while saidpower line is inoperative so that stored thermal energy in said workingfluid and said predetermined amount of kinetic energy are converted topower for said load upon loss of line power.